A Novel Hybrid Multilevel Converter for Medium Voltage Applications

This paper presents a new hybrid multilevel converter suitable for interconnecting dc systems and variable speed drives applications. The structure of the topology is a hybrid of two level converter and the modular multilevel converter (MMC). The proposed converter can provide a three-phase trapezoidal output voltage with a controlled slope while using a single MMC leg only. Therefore, the use of only one-third of the sub-modules (SMs) compared to MMC, reduces the overall size of the converter. The front to front configuration of the proposed converter provides the desired voltage conversion, grounding flexibility and dc fault blocking capability due to the isolated structure of the dc-dc converter. Moreover, the soft switching operation of the phase leg switches and the bidirectional switches (BSs) supports the suitability of the proposed converter. Performance evaluation of a dc-dc converter based on the proposed topology is carried out in PSCAD/EMTDC and analyzed in detail.

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